When launching the new iPod touch, Apple surprised by including in it for the first time in a long time a newer version of the Bluetooth standard, 4.1. Less than two months ago, however, an information leak at the FCC (Federal Communications Commission, or Federal Communications Commission) showed new Magic Mouse and wireless keyboard equipped with Bluetooth 4.2 a faster version of the technology and with other benefits.
More recently, we saw that although the new Apple TV continues with Bluetooth 4.0, the iPad mini 4 already came with 4.2. And now Apple has updated the comparison pages for iPhones and iPads indicating that, in fact, all recent models are equipped with the latest version of the technology.
Note that this includes not only the iPhones 6s and 6s Plus, but also the 6 and 6 Plus; similarly, in addition to the iPad mini 4 and obviously the iPad Pro, the iPad Air 2 also came into play.
The question remains: did Apple find a way to update the Bluetooth version of these devices via software, or did it actually make a change in the production line of previous models, replacing the component responsible for Bluetooth? As there is no way to check on iOS which version of Bluetooth, only Apple itself can clarify that.
Remember that in June, Apple became a member of the Bluetooth SIG (Special Interest Group, or Special Interest Group).